Control apparatus for combined fluid compressors and free piston machines



Jan. 19, 1954 BENT 2,666,569

CONTROL APPARATUS FOR COMBINED FLUID COMPRESSORS AND FREE PISTON MACHINES Filed May 25, 1948 2 Sheets-Sheet 1 IN V EN TOR.

3 Arthur JBem:

ATTORNEY Jan. 19, 1954 J. BENT 2,666,569

CONTROL APPARATUS FOR COMBINED FLUID COMPRESSORS AND FREE PISTON MACHINES Filed May 25, 1948 2 Sheets-Sheet 2 m R 6 m MB R m 0 ow W mm 1 r 6 A m u .m .m w .H M V. B a 3mm mm 31% m3 3 50 3 \8 o n g 3Q mmt ow Km 3 6 Kw R N @w NQSQS Q N Q0 v w @Q a NM" Ema wnw w Em on ww N mw Patented Jan. 19, 1954 CONTROL APPARATUS FOR COMBINED FLUID COMPRESSORS AND FREE PIS- TON MACHINES Arthur- J. Bent, Pittsburgh, Pa., assignor to West-- inghouse Air Brake Company, a corporation of Pennsylvania Application May 25, 1948, Serial No. 28,996

9 Claims. (Cl. 230-,-56)

This invention relates to free piston machines and more particularly to the type for compressing air and the principal object of the invention is the provision of improved means for controlling starting and running thereof.

More particularly the invention relates to control apparatus arranged for operation by an operator to effect starting of a free piston air compressor and means automatically operative after starting to control running of the compressor in accordance with the pressure of views of positioning and locking cylinders, re-

spectively, shown in elevation in Fig. 1; Fig. 5 is a sectional view of a direct bounce governor device shown in elevation in Fig. 1; Fig. 6 is an enlarged view of a portion of said direct bounce governor device; and Fig. 7 is a diagrammatic View of a timing valve device shown in elevation in Fig. 1.

Description In the drawing, reference numeral I indicates generally a free piston machine of well-known structure comprising a casing containing two opposed and identical, diesel type operated, air compressing units 2 and 3 each of which comprises a power piston l and integrally connected 1 air compressing and direct bounce pistons 5 and 6, respectfully. The two power pistons 4 cooperate with the casing of the machine to form a power chamber 1 into which fluid is adapted to be injected by way of a nozzle 8 for compression ignition upon said pistons obtaining a chosen inner position. The power thus developed is adapted to drive the piston assemblies of the two units outwardly on an air compressing stroke. As the power pistons thus move outwardly they are adapted to first uncover an exhaust port 9 for escape of burnt gases from chamber 1 and then a scavenger port Eilto allow entry of fresh air to said chamber for scavenger purposes.

At the power piston side of each air compressing piston 5 is a scavenger compressing chamber ll having a connection with atmosphere by way of an inlet valve 82 and a discharge connection with a scavenger "receiver it by way of a discharge valve i l, the scavenger receiver being connected to said chamber inboth compressing units and to the scavenger port It in the casing, whereby during running, reciprocation or" pistons 5 will constantly provide a supply of compressed air for scavenging the power chamber 3.

At the opposite side of each air compressing piston 5 is an air compressing chamber [5 having an intake opening with atmosphere past an inlet valve ltand a delivery opening past a discharge valve ii to a compressed air receiving pipe E8. The pipe i8 is connected to the air compressing chamber E5 in both compressor units, to a storage reservoir Mia and to a control valve device l9. It will be apparent that upon running of the two compressor units 2 and 3, reciprocation of the air compressing pistons 15 will'alternately draw air from atmosphere past inlet valves it into chambers l5 and then compress such air past the discharge valves ll into pipe 58 and storage reservoir Illa. The storage reservoir I806 constitutes a source of compressed air for any desired purpose.

At the outer end of each direct bounce piston G is a direct bounce chamber 26 in which air is adapted to be compressed on the outward power and air compressing stroke of the two piston assemblies to provide energy for stopping said pistons and for returning them on a compression stroke to provide compression ignition. The two direct bounce chambers 2t are in permanent communication with each other by way of a pipe 2i which also connects with the control valve device Ill.

The piston assemblies of the two air compressing units are connected together for symmetrical movement by two pairs of oppositely operating toothed racks 22 and 23 cooperating with an interposed pinion gear 2 secured to operate a rock shaft 25 which may be journaled in the casing of said units. The pairs of racks may be arranged at opposite sides of the power pistons 4 with the two racks 22 connected at one end to a bar 25extending through an opening in one of said pistons and suitable slots 2? in the casing,

while the two racks 23 are connected at one end to a similar bar 28 extending through an opening in the other piston i and similar slots 29 in the casing, said slots being of such length as to permit full stroking of the piston assemblies without fouling on the casing. lhe bar as is rigidly connected to the respective piston i and secured thereto at its center by a pin 26a while the open- I ing in the other piston through which the rod 28 extends is wider in the direction of the axis of the piston than the width of rod 28 to permit rod 28 to rock slightly on a pin 28a secured atits longitudinal center to the respective piston 4 for equalizing pressure transmitted by both rods 23 and to the respective racks 22, 23.

The casing is provided beyond each direct bounce chamber 23 with a safety space which during normal running of the compressor constitutes a part of said chamber. The safety spaces 30 are adapted to receive the direct bounce pistons t in case of overstroke of the piston assemblies during running to provide an air cushion to stop the assemblies before contact of said pistons with the end walls of said spaces. Also in starting the compressor 1 the direct bounce pistons 6 are adapted to move into the safety spaces, 30, as will be later described. 4

For moving the piston assemblies apartto their extreme outer positions for starting the compressor and in which the direct bounce pistons 6 will be disposed in the safety spaces 30 two like positioning cylinder devices 34 and 32 are provided. For illustration purposes, these cylinder devices are shown at the same side of the compressor and oppositely arranged for acting on the opposite free ends of the respective racks 22, 23.

Each of the positioning cylinder devices 3|, 32 comprises (Fig. 3) a casing containing a piston 33 provided with an axially arranged cylindrical piston rod 34 extending through and having sliding contact with a bearing element 35. A precompressed spring 36 encircling rod 34 is supported at one end on element While its opposite end bears against one side of piston 33 for urging said piston to a normal or rest position, in which it is shown in the drawing, when a pressure chamber 37 is void of fluid under pressure. The bearing element 35 is held in the casing against the force of spring 36 by engagement with a ring 38 secured in the casing. Substantially midway of the length of piston rod 34 said rod has a stop shoulder 39 arranged for contact with the bearing element 35 to limit movement of piston 33 against spring 35.

Slidably mounted in the piston rod 34 is a piston 43 one side of which is open to chamber 31. Extending from the opposite side of piston 40 and through a suitable bearing provided in .a closed end wall 42 of rod 34 is a rod 4 I. Slidablymounted on the rod 41 within the sleeve 34 is a spring supporting device 43 subject on opposite ends to pressure of two oppositely extending compressed coil springs 44, 45, respectively, which encircle the rod l l The spring 44 is supported at the end opposite that engaging the supporting device 43 by the end wall 42 of piston rod 34, while theopposite end of spring 45 bears against the piston 40, the purpose of said springs being to urge said piston to the position in which it is shown in the drawing with respect to piston 33 when chamber 31 is void of fluid under pressure. To prevent piston 40 moving out of its cylinder a ring 45a is secured to rod ll outside of the casing for contact with the closed end wall 42 of the cylindrical rod 34.

The rods 4! of the two positioning cylinders 31 and 32 are arranged for engagement with the ends of the respective racks 22 and 23. When, as during running of the compressor, the rods are in their fully retracted position, in which they are shown in the drawing, racks 22, 23 are adapted to reciprocate with the power pistons 4 without contacting said rods. For starting the machine, preparatory to running, fluid under pressure is adapted to be supplied to pressure chambers 31 in the two positioning cylinders 3|, 32 through a common pipe 43 by operation of the control device IQ. In each positioning cylinder device the pressure acting on the piston 33 is adapted to move said piston against spring 33 until shoulder 39 engages the bearing element 35 for projecting the cylindrical rod 34 from the casing. At substantially the same timeythe piston id will be moved in the rod as by pressure of fluid in chamber 3! and actuate its rod 4! first into contact with the respective rack 22 or 23 and then through said rack move the respective piston assembly d, 5 and 6 to the position preliminary to starting in which said piston ii will be disposed in the respective safety space 30.

A fluid pressure operable, spring released, locking device i! is associated with each of the opposite ends of the two rods 26, 2% for cooperation therewith to hold the two piston assemblies in their outermost position-s preliminary to starting, against pressure of fluid in the direct bounce chambers 23 which will become effective by leakage into the safety spaces 33 over the ends of the direct bounce pistons 5, as will be later described.

Each locking device (Fig. 4) comprises a casing 48 adapted to be fixed with respect to the compressor casing. Slidably mounted in casing 63 is a piston 39 provided at one side with a rod 53 extending through a non-pressure chamber 55 and a suitable bore in the end wall thereof to the exterior oi the casing. A precompressed spring 52 contained in chamber 5| and encircling rod 53 is supported at one end on the casing and bears at the opposite end against one side of piston se for urging said piston to its normal rest position, in which it is shown in the drawing, upon release of fluid under pressure from a pressure chamber 53 at the opposite side of said piston. Movement of piston 29 in the opposite direction against spring 52 is adapted to be limited by contact between said piston and a boss 49a en circling the rod The pressure chambers 53 in the several locking devices are all connected to a common control pipe 5 5' leading to the control device is. In practice the distance by way of pipe 54 from the control device !9 to all of the locking devices 41 is substantially the same in order to provide for operation of said devices in unison.

Each locking device t? further comprises an arm 55 projecting from casing 43 and fulcrumed on a pin 55 carried by said arm is the knee of a bell crank 51 the end of one arm of which is connected by a pin 53 to the projecting end of piston rod '50. A roller 58 is mounted on a pin 63 carried in the end of the other arm of bell crank ill. The locking devices 47 adjacent the opposite ends of bar 26 are disposed with the ends carrying the rollers 53 arranged opposite to the ends carrying the rollers in the other two locking devices, and each of the opposite ends of the two bars 25, 28 is provided with a locking surface 61 for contact by the respective roller 59 with the piston is in contact with the stop boss 53a in their respective locking device, said piston being movable to this position against spring 52 upon supply of fluid under pressure to chamber 53 by way of pipe 54 as will be hereinafter described. The ang-ularity of surfaces 3! with respect to the angular posi tion of the respective bell-cranks 5? when pistons 49 are in contact with goss tits is such as to permit pressure of fluid in the direct bounce chm.-- bers 2i! and safety spaces 33 acting on the piston assemblies and through the rods 28, 28 on the rollers 53 in the locking devices 4'5 to displace said rollers out of the path of novement of said rods, when fluid under pressure is released fromof any well-known type arranged to be operated by a cam 63 on the rock shaft 25 at the proper point in the inward stroke of the piston assemblies to supply fuel to the power chamber 1 by way or". nozzle 8 to provide compression ignition for driving the piston assemblies apart on their power, air compressing stroke. Adjustment of the injector 62 to vary the fuel supply is obtained by a conventional rack 64 having a run position such as that in which it is shown in the drawing to provide a maximum amount of fuel for starting and normal running of the machine and being movable into the injector for'reducing the fuel supply.

According to the invention I provide apparatus for controlling operation of the structure so far described, and thereby for controlling compressing of air by the free piston units 2, 3 into the storage reservoir [8a and for automatically limiting the pressure in said reservoir during running of the machine.

The invention comprises in part the control valve device It, above mentioned, Which in turn comprises a bracket 65 upon which is mounted a manually operable operators starting valve device 56, a feed valve device 61a of any wellknown structure, a vent valve device 61, a shuttle valve device E8, a sequence valve device 69 and an unloading valve device ll The operators starting valve device 66 (Fig. 2) comprises a casing having a chamber H containing a supply valve 12 arranged to cooperate with a seat 73 for controlling communication between said chamber and a chamber 14 byway .of an axial passage 75 encircled by said seat and one or more passages 16 connecting passage 15 to chamber 74. A release valve ll contained in chamber 74 is arranged to cooperate with a seat on the end of an axially movable cylindrical plunger l8 for controlling afluid pressure release communication between said chamber and the interior of said plunger which is open to atmosphere through a radial port 19 in the plunger, a chamber 30 encircling said plunger and a passage 8|. A pin 82 of small diameter and extending through the axial bore 75 connects the adjacent side of the supply and release valves 12 and Ti. A spring 83 in chamber H acts on the supply valve 12 for seating it. A casing shoulder 84 is provided for contact by the release valve H to permit plunger 18 to move away from it for opening communication past said valve from chamber M to the interior of said plunger and thereby to atmosphere.- 7

The end of plunger 18 opposite the seat for I release valve ll extends through a bore in a cap nut 85 for engagement by an operators lever 86. Within the chamber 80, a collar 81 on plunger l3 is provided to contact cap nut 85 to limit unseating movement of said plunger from the release valve, and a spring 88 contained in said chamber and acting on said collar is provided to .eiiect such movement of said plunger.

The operators lever 85 has at one end a slot 89 and extending through said slot and carried,

by the casing is a fulcrum pin 90. The lower end of lever 85 is beveled and interposed therebetween and the casing isa spring 9! which is under pressure and which has a line'of action passing'through said lever below the axis of pin 9Q, whereby the spring not only acts to elevate the lever on said pin but also urges it in acounter-clockwise direction about said pin. The

lever 86 has a protecting boss 92 for engaging the casing in the elevated position of said lever to hold the lever out of contact with the projecting end of plunger 18. Depressing of lever 86 downwardly against spring 9! to a position defined by pin engaging the opposite end of slot 3-5 will align the boss 86 for engagement with plunger 18.

.The supply valve chamber H is open to a fluid pressure supply passage 93 adapted to be constantly supplied with fluid at a chosen pressure, such as 5G0 pounds, by operation of the feed valve device filo: to supply fluid thereto from a source of higher pressure such as 650 pounds normally contained in a high pressure reservoir as and connected .to the feed valve device by a pipe 95. The release valve chamber is is open by way of a passage I65 to pipe 45 connected to the positioning cylinder devices 3|, 32.

The vent valve device E5? comprises a valve 95 contained in a chamber 9'! for controlling communication between said chamber and a chamber 98a which is open to atmosphere through a passage 99. Chamber 5'! is open by way of a passage use in the bracket 65 to pipe I8 leading to the air compressing chambers l5 and storage reservoir lBa, as well as to the unloading valve device it. The vent valve device further comprises a piston ill! connected by stern N32 to valve 95 and open at one side to a pressure chamber 33 which is connected to the bracket passage I08. Upon supply of fluid under pressure to chamber 163 the piston It! is adapted to unseat valve 96 for opening chamber El to'the atmospheric passage 99. A spring Hi l acting on piston Hill is adapted to operate same upon release of fluid under pressure from chamber I53 to permit seating of valve 96 by a spring 96a. The piston chamber N13 is open to passage [06.

The shuttle valve device 68 comprises a poppet valve I26 contained in a chamber i2! which is open by way of a passage 528 to pipe 2| leading to the direct bounce chambers 26. The valve I26 is arranged to cooperate with a seat [25 at one side for controlling communication between chamber l2? and a pipe 328a leading to a direct bounce pressure governor device 38. The valve I26 is cooperative with a seat l3! at its opposite side to control communication between chamber l2? and an atmospheric passage E32.

The valve H6 is connected to one end of a stem I33 extending through the encircling seat I35 and then through a bore in the easing into a chamber I34 at one side of a piston IE5 to which the opposite end of said stem is connected. A spring its in chamber I34 acts on piston I35 for actuating same to unseat the valve I28 from seat H9 and to seat it on seat l3l when a chamber I3? at the opposite side of said piston is void of fluid under pressure. Upon supply of fluid under pressure to chamber l3? the piston is adapted to shift valve lit into engagement with seat I 29.

The sequence valve device 39 comprises a poppet valve it! contained in a chamber its which is open to pipe 54 leading to the locking devices 41. The valve N11 has two positions in one of which it is arranged to cooperate with a seat N19 for disconnecting chamber W8 from an atmospheric passage H9 and for opening said chamber through a seat Hi to a passage H2 connected by a pipe H3 to a timing valve device H4. 7 In the other position of valve iii? in which estates 7 it will be in engagement s'eat I II the chamber IE8 is adapted to be disconnected from pas= sage H2 and opened to passage III].

The valve I01 is connected to one end of a stem II extending through the seat-III, passage H2 and a bore in the casing. Connected to the opposite end of stem I is a piston III; for moving the valve I01 to it's diiier'ent positions, said piston being slidably mounted in a bore through an element I'I1 secured in the casing of the device and separating a chamber I2'IJ at the side of said piston from which the stem Hi5 projects from an atmospheric chamber I 2'I at the opposite side. The chamber I is provided around an annular seat rib I23 and within said rib is a chamber I24 encircling the stem I15 and open to passage I28. The diameter of the seat rib I23 is less than that "of piston IIB so that when said piston is in contact therewith less than the full face of the piston will be exposed to chamber "E24 within said rib. When the piston He is disengaged from seat rib I23 chambers I28 and I2 are in efie'ct one chamber. A spring I contained in chamber IZI acts on the piston IIS for urging it into contact with seat rib I23 with a chosen force.

The unloading valve device 10 comprises a check valve Idl contained in a chamber I42 and arranged to control communication by way of a bore I43 between said chamber and a passage I 54. The passage I 44 is connected on the one hand through an air strainer I45 to passage I00 and thence by way of pipe I8 to the storage reservoir Illa, and on the other hand, to an air intake pipe M6 for a high pressure auxiliary air compressor Mi. A discharge pipe I43 from the compressor I-I'I is connected to chamber I42 in the unloading device 18.

In the unloading device "III a bias spring I49 acts on the check valve I II for urging it to its seat. Extending through the passage I44 and bore I43 and engaging the check valve MI is a pin ltd which is connected to a piston I5I slidably mounted in the casing. At the check valve side of piston I553 is a non-pressure chamber I52 open to atmosphere through a vent I53 and containing a spring I54 acting on said piston for urging it with a chosen force in a direction away from check valve Il to permit seating of said valve by spring I49, such movement of said piston being limited by contact with the casing. A ring seal I530; carried in the casing has sealing and sliding contact with the peripheral surface of pin I53 to prevent leakage of fluid under pressure from passage I to the atmospheric chamber I52. At the opposite side of piston 'I5I is a pressure chamber I540, which is open to a passage I55 in turn open to pipe 95 leading to the high pressure reservoir '94.

Associated with the unloading device "is .a check valve I55 contained in a chamber I51 for closing communication between said chamber and a passage I53 connecting the unloading check valve chamber I l-2 to the discharge pipe I48 from compressor I41. A bias spring I59 in chamber I51 acts on the check valve I56 for urging it to its seat. The chamber I31 is open to passa elst.

The high pressure air compressor I41 may be of any suitable type capable of operation by oscillation of shaft 25, which is driven by the free piston machine I through the medium of one of the pairs of racks 22, 23 and the interengaging pinion 2%, to take air under pressure from pipe I43, and hen'ce'from the storage resenvoir I8a, and to compress it to ahigher pressure into pipe I48 and thence into the high pressure reservoir 9!. "The pressure of air in the storage reservoir I8a, as charged by the rree piston ma chine as will be hereinafter described, may be of any degree up to for example 100 pounds but normally between for instance and pounds, While that delivered by the compressor I41 for supply to the high pressure reservoir 94 may for exam le be around 650 pounds.

The direct bounce governor device I39 (Fig. 5) may comprise a casing having a chamber I55 arranged to be constantly supplied with fluid from the high pressure reservoir 94 at the reduced pressure provided by the feed valve device 6111 by way of passage 93 in the control valve device I8, a pipe Iii I and 'a passage I52 in said governor device. The chamber I50 contains a supply valve I63 arranged to cooperate with a seat I64 for controlling new or fluid under pressure from said chamber to a chamber I65 which is open by pipe I230; to the shuttle valve device 68. Encirclin'g the seat I64 is an element I65 having a bore in which the valve I53 is adapted to move, said bore being tapered outwardly iroin said seat for cooperation with said valve to provide a controlled and variable degree of opening past said valve according to the degree it is unseated from seat Kid. A stem I61 has one end connected to valve I63 and a spring I68 contained chamber I'EII acts on said stem for urging said valve toward seat I 64. The stem I61 is connected with and projects from one side of a piston Hit through the chamber I'fiIi and is constantly subject on said one side to pressure of fluid in said chamber. The opposite side of piston ltd is subject to pressure of fluid in a chamber II-t which is constantly open through a choke I1I in said piston and a passage I12 in stem I 51 to chamber I60.

A poppet valve I13 contained in a chamber I14 open to chamber I16 is arranged to cooperate with a seat in the casing to control communication between said chamber I1 3 and a passage I15 which is open to chamber I55 A release valve I16 (Fig. 6) coaxial-1y arranged with respect to but spaced from the valve I13 is adapted to cooperate with a seat on a movable element I11 for controlling a fluid pressure release communication between passage I15 and a passage I18 in said element. A plunger I'I9 slidably mounted in a suitable bore in the casing has opposite ends in engagement, respectively, with the valves I13 and HE. A spring I80 contained in chamber I141 acts on the valve I13 for urging it toward its casing seat. A shoulder ISI in the casing is arranged for contact by' valve Ht to perm-it unseating of the element I'i1 therefrom.

The element I1! is slidably mounted in a bore in the casing and has a sealing ring I82 in sealing and sliding contact with the Wall of said bore to prevent leakage of fluid under pressure between passage I15 open to one side of said ring and a chamber 1-83 at the opposite side. The element I1 1 constitutes an extension of a diaphragm follower I3 3 contained in chamber I83 and clamped centrally to one side of a flexible diaphragm I35 by the cooperation thereof and a securing nut I86 engaging the opposite side of said diaphragm. The diaphragm is clamped around its edge in the casing with chamber IE3 at one side and a charm ber I81 at the opposite side. Chamber I83 may be open by way of a pipe I88 to one of the two direct bounce chambers 20. The pipe I38 has a relatively small flow capacity so that upon reciprocation of the two direct bounce pistons B, as will be hereinafter described, a substantial escapee 9 mean of the pressure developed in said direct bounce chambers at opposite ends of the stroke of said pistons will be constantly effective in chamber I83 on the one side of the diaphragm. Chamber I? at the opposite side of the diaphragm may be constantly supplied with fluid under pressure from passage IE2 by way of a choke use. I

The diaphragm follower I8 5 comprises a stud 7 portion Iii extending centrally through the diaphragm for cooperation with the nut I86 and said stud portion has an axial counterbore to which passage I18 from the release valve IIG opens and in which is slidably mounted one end of a fluid conductor ESI. The fluid conductor extends through chamber I8! and its opposite end is slidably mounted in a casing bore which is open to atmosphere through a passage I 92, whereby passage H8 is constantly vented. The opposite ends of the conductor Isl are spherical and each carries a sealing ring I 93 having sealing and sliding contact with the wall of the respective bore for preventing leakage of fluid under pressure from one side to the opposite side of the ring. The cross-sectional area of the end of the conductor I8! disposed in the bore of the follower stud I96 is greater than the cross-sectional area of the movable element III, so that the'area of the diaphragm subject to pressure of fluid in chamber I82 is somewhat less than that subject to pressure of fluid in chamber I83, whereby in case of equal pressures of fluid in chambers I83, ISL a slight bias force will be provided acting in the direction of chamber I SI.

The directbounce governor device I33 further comprises a member I94 adjustably mounted in a bore in the casing and having a, counterbore I95 closed at one end by a plug ass, while extending from the opposite end through a plug i9? secured in one end of said bore and into an atmospheric chamber IE8 is an adjusting stem Ids. The plug I96 has an axial bore encircled within counterbore I85 by a valve seat provided for engagement by a poppet valve 26% contained in said counterbore. A bias spring Zfil in counterbore I95 acts on the valve sec for urging it to its seat. Counterbore 95 is constantly open to diaphragm chamber I8? by way of one or more ports 262 therethrough, an annular cavity 283 provided in the exterior surface of plunger I94 and a passage 284.

A. bias spring 265 contained in chamber E98 is interposed between the casing and a washer 266 secured to stem I99 for holding said stem, the plunger I 9% and the associated seat for valve 268 in. a chosen position in the casing determined by adjustment of an adjusting screw 29'! screwthreaded in the casing and extending into chamber I98 wherein it engages the end of stem I99.

At the outer or right-hand end of plug I96 is a chamber 238 open by a passage 298 to a chamber 21s at the opposite end of plunger 19d, said passage being also open to passage I15, and thence to chamber I 65 and thereby the direct bounce chambers 29. Suitable sealing rings 2H carried by the plunger I94 are provided to prevent leakage of fluid under pressure from cavity 233 to eitherchamb-er 2% or 2 I0.

A plunger 2I2, slidably mounted in suitable bores in the casing in coaxial alignment with the valve 299;; in the governor device I30, is so disposed that the end of said plunger projecting from said device is aligned for engagement by the end of one of the racks for instancea rack 22 as shown in the drawing, near the end of the compressionstroke of the power pistons The plunger 2E2 comprises a relatively large portion 2I3 terminating in a chamber 2M wherein one end is connected to a smaller part 2I5 which projects outside of the casing for engagement with the rack 22. Projecting from the opposite end of the large portion 2I3 into chamber 208 is a smaller portion H6 and projecting from the smaller portion 216 is a portion ZI'I extending through chamber 208 and, with clearance, through an axial bore in plug I96 for engaging the poppet valve 206. Chamber 2M is open through a passage 2 Ha to the annular cavity 203 so as to be constantly charged with fluid under pressure from diaphragm chamber I81. The area of plunger 2I2 thus subject to pressure of fluid in chamber 2M is slightly greater than the area subject to pressure of fluid in chamber 28% whereby a force is created which will constantly bias said plunger in the direction of and against the valve 200 but insufficient to unseat said valve against spring 20 I.

The timing valve device I54; except as hereinafter noted, may be identical to the starting valve device 66 and the fluid pressure supply pipe IE! is connected to the supply valve chamber II thereof while the pipe H3 is connected to the release valve chamber I4.

The plunger I8 of the timing valve device H4 is however, provided with an enlarged piston-like portion 23I (Fig. 7) subject on one end to pressure of fluid in the release valve chamber I 4 and on the opposite end to atmoshperic pressure in chamber 8%. The area of portion 23I is such that when subject to pressure of fluid in chamber I4, said portion will move the plunger 18 against spring 88. The shoulder as for contact with the release valve, I! to unseat it from the end of plunger I8 is so disposed as to permit a greater movement of said plunger after seating of the supply valve i2 before unseating of the release valve I1 occurs than is the case with the starting valve device 66, for reasons which will be hereinafter described. A light bias spring 232 acts on the release valve I? to urge it out of contact with shoulder and into contact with pin 92 upon release of fluid under pressure from chamber I l.

The timing valve device I I is so arranged with respect to the free piston machine that the plunger I8 thereof will be operated, as by engagement of the rack connecting bar 28, to close the release valve iI and open the supply valve I2 when, and only when, the direct bounce pistons are at the end of their outward stroke disposed in the safety spaces as, and to permit closing vof said supply valve upon slight movement in the opposite direction followed by opening or" the release valve after the direct bounce pistons t are urged out of the safety spaces 353 a chosen distance.

A motor ZIS is provided for adjusting the rack es of the fuel injector 62. This motor comprises a casing containing a flexible diaphragm 24s at one side of which is a chamber 223 open to pipe I8 whereby said diaphragm is adapted to be constantly subjected in said chamber to the pressure of fluid in the storage reservoir liid.

t the opposite side of diaphragm 2 l 53 is a nonpressure chamber 223 containing a plunger 22d engaging at one end the adjacent side of diaphragm ZIS and extending outwardly from the casing with its opposite end operatively connected to a lever 222 between its ends. One end of lever'222 is fulcrumed to a lug 225 projecting from the casing of the motor while its opposite end isoperatively connected by a link 2% to-rack of the fuel injector A shoulder 221- on stem is provided for engagement with a stop nut adjustably secured in the casing for limiting movement of said stem and of diaphragm Bit by pressure of fluid in chamber 220 to a degree for positioning lever 222 and thereby the fuel raclr be to what may be called an idle position. A spring 229 in chamber 223 acts on diaphragm 219 in opposition to: pressure of fluid in chamber 225.

The pressure of spring 229 is such as to prevent movement of the; diaphragm from the position in which it is shown in the drawing while the pres sure of fluid in the storage reservoir ifia acting in chamber 229 is less than the chosen pressure, such as iii pounds. When the pressure of fluid in reservoir [5a and chamber 226 is increased to above this chosen pressure the diaphragm 2H3 is adapted to be deflected thereby in accordance with such increase until at the time a chosen higher pressure, such as 100 pounds, is obtained the shoulder 22'! on plunger 224 will contact stop nut 22%. With the diaphragm 226 in the position in which it is shown in the drawing the lever 222 and rack 54 yill be positioned to supply the maximum amount of fuel to the nozzle 8. It will therefore be seen that for starting the free piston machine and during running thereof until the pressure of fluid in the storage reservoir Ilia is increased to the chosen pressure of 90 pounds the supply of fuel to the machine will be constant and of a maximum degree, following which the fuel supply will be reduced in proportion to further increase in pressure in reservoir lea until at the time the higher pressure of 1% pounds is reached the fuel supply will be so reduced that the machine will merely idle. When idling there will be no discharge of air from the air compressor chambers 15, as will be brought out later in detail.

A cut-out valve 235i is. provided in. the connection of pipe to the feed valve device 557a for closing communication between said pipe and feed valve device when the free piston compressor units are stopped and for opening said communication for starting and. during running of said units.

Operation In operation, let it be assumed that the free piston air compressor is stopped and that the high pressure reservoir 9 is charged with fluid at substantially normal pressure, such as 658 pounds, from previous operation of the auxiliary high pressure compressor M! in a manner which will become later apparent. 'When the high pressure reservoir charged with fluid under pressure it will be noted that the check valve I53 associated with the unloading valve device iii functions to hold the fluid in said reservoir against reverse flow through passage I55, When the free piston compressor is stopped the cutout valve 23% will also be closed: to disconnect the high pressure reservoir 94' from. the feed valve device 67a.

In order to prepare for starting the free piston compressor, the cut-out valve 239 will be opened to permit fluid under pressure from the high pressure reservoir to flow to the feed. valve device Ella which will operate to supply fluid therefrom at the desired reduced pressure, for example 500 pounds, to passage 93 and thence to chamber H in the starting valve device 55 and also from said. passage to pipe. [SI leading to the corresponding chamber ll in the timing valve device H4, and'let it be further assumed that the supply valve 12 in both of said devices is seated at this time.

Fluid supplied bythe feed valve device bid to pipe Hi! will also flow into chamber we and gradually through choke i539 into chamber 18'! of the direct bounce governor device Lib.

When the free piston compressor is stopped, in a manner which will be later desc ibed in detail, the piston assemblies will be substantially in their innermost position and valve 235 in the direct bounce governor device 139 will therefore be open sufliciently to dissipate to atmosphere past the valve H8, which will be open, the fluid under pressure thus supplied to chamber lll'l, at a rate exceeding the rate of supply through choke I89, so that there will be no change in position of the parts of the direct bounce governor device upon initially opening the cut-out valve 230.

To now start the free piston air compressor the operator will grasp lever 35 and turn it about pivot pin 9!? in a clockwise direction against the force of spring 9! until the lug 82 on said lever clears the projecting end of plunger 73.. The lever 86 will then be depressed against the spring 9! until the lug 92 aligns with the end of plunger 18 in the starting valve device 66 following which said lever will be rocked in a counter-clockwise direction for actuating said plunger into seating engagement with the release valve H to close the atmospheric connection to chamber '54 and to then actuat pin 82 to unseat the supply valve 72. Fluid under pressure from the feed valve device, 51a present in chamber ii will then flow past the supply valve E2 to the release valve chamber M and thence intopassage Hi6.

Fluid. under pressure thus supplied to passage I06 will flow to piston chamber H33 in the vent valve device 6'5 and there act on piston till to move it against spring we for unseating the valve 96 against spring 96 Upon unseating of valve 95 the air compressing chambers E5 in the free piston air compressor I and the storage reservoir 18a will be opened to atmosphere through pipe Ill and passage its leading to the valve chamber 91 and thence past the open valve 95 to chamber S811 andlthrough the atmospheric passage 99, it being apparent that the air compressing chambers l5 are open to pipe it past the discharge valves ll therefor. The storage reservoir 18a is preferably of relatively small volume, such. as 5 cubic feet as will be employed in connectionv with certain portable air compressing units, so that if partially charged at the time of starting the compressor the dissipation of such fluid by operation of the vent valve device til as just described, will not be material. If the reservoir 18a were of greater volume, as might be employed in a stationary air supply system, a check valve (not shown) might be provided between said reservoir and pipe it to hold fluid pressure in said reservoir at the time of venting said pipe through the vent valve device 6?.

Fluid'under pressure supplied to passage I05 by operation. of the starting valve device 66 will also flow through choke Mil into chamber 139 and thence through passage I38 into piston chamber I3! of the shuttle valve device 65. The flow capacity of the choke Mil and size of volume 639- are so related that suiilcient pressure will be obtained in chamber E3? of the shuttle valve device 6,8 to move piston [35 against spring we immediately following opening of vent valve 96 in the vent valve device 61, although the piston I35 may operate in unison with piston IuI under the present condition; The movement of piston I35 against spring I35 will shift the valve I26 out of engagement with seat I3I and into engagement with seat I 29 thereby disconnecting pipe 2! and the direct bounce chambers 29 from pipe I28o leading to the direct bounce governor device led and opening the former pipe and thereby th direct bounce chambers to the atmos-pheric passage I32, it now being seen that both the direct bounce chambers 20 and the air compressing chambers I=5 in the free piston air compressor I are open to atmosphere.

Fluid under pressure supplied by the starting valve device 55 to passage Its will also flow through pipe at to the two positioning cylinder devices 3| and 32 and actuate th pistons 33 and 46 therein to move the respective rods 42 into contact with the ends of the respective racks Z2 and 23 and then through said racks actuate the bars 26 and 28 to move the two piston assemblies of the air compressor in a direction away from each other and to the position for starting in which the direct bounce pistons 6 will be disposed in the respective safety spaces 3% in contact with the end Walls thereof, it being noted that such movement is unopposed by pressure of fluid in either the air compressing chambers I5 or direct bounce chambers 23 since said chambers are open to atmosphere and vented at this time. As the two power pistons Q are thus moved apart the power chamber 7 will be first opened to the exhaust port 9 and then to the scavenger port I!) insuring a charge of fresh air in said chamber irom the scavenger receiver 53.

As the two piston assemblies are moved from their innermost position to their outermost position for starting, by operation of the positioning cylinder devices 35 and 32 as just described, the movement from the innermost position will withdraw the one rack. 22 from contact with plunger 2 I2 in the direct bounce governor device 535 whereupon spring 26! will seat valve 296 to prevent further venting of fluid under pressure from diaphragm chamber I82. The pressure of fluid in chamber Iil'i will then increase by the supply through choke I lit to substantially the same pressure as provided by the feed valve device tl'a in passage I62 and this pressure acting on diaphragm I85 will deflect said diaphragm to close valve Eli; and open valve I73. Upon opening of valve I'it fluid under pressure will be vented from piston chamber flu to passage I15 and thence to chamber Hi5 and pipe 528a at a rate exceeding the rate of supply to chamber iii; through choke iii in piston i whereupon the higher pressure of fluid in chamber Ifiil acting on the opposite side of piston i555 will actuate said piston to open the supply valve 5 6;? to permit flow of fluid under pressure from chamber ltd to chamber I65 and pipe 128a. As the pressure of fluid in chamber I65 is thereby increased it will reduce the flow from piston chamber i'iii past the open valve I13 and permit the pressure in chamber ill! to increase by flow through the choke Ill, until finally the difierential in pressures in chambers ill! and IE at opposite sides of the piston I69 will become reduced to a point where spring I68 will close the supply valve B63. Following closing of the supply valve 563, the pressure in chamb r 185 and pipe i28a will equalize through choke HI in piston I59 and past the open valve '53 with that in the supply passag [6-2. The valve I73 will remain open at this time under pressure of fluid in chamber E87 acting on diaphragm I85 since chamber I63 at the opposite side of the diaphragm is vented with the direct bounce chamber 29 through the shuttle valve device 63.

With the valve I26 in the shuttle valve device 68 seated on seat I29 the supply valve E53 in the direct bounce governor device will be only momentarily opened for charging the relatively small volume of chamber IE5 and pipe Itta under the condition being described. This operation of the direct bounce governor device I39 is not significant at the stage in the starting operation under consideration, but the'purpose will be brought out hereinafter.

By the time the direct bounce pistons 6 move into contact with the end wall of safety spaces 36, under action of the positioning cylinder devices 31, 32, the bar 26 connecting the racks 22 will have engaged plunger 78 in the timing valve device I I4 and actuated the valves therein to establish communication between pipe I6I supplied with fiuid under pressure from thefeed valve device 61a and pipe H3 leading to the sequence valve device 69. Fluid under pressure will thus be supplied to pipe MS from which it Will flow through passage H2 in the sequence valve device 69 and past the valve it? therein which at this time is unseated from seat i i i, to pipe 56 leading to the locking devices d7. Pressure of fluid thus obtained in piston chambers 53 of the locking devices will actuate pistons i9 against springs 52 for operating the bell cranks 57 to move the rollers 58 into position for contact with the respective surfaces 6! on the rods 25 and 23 with a force which will hold the two piston assemblies apart upon subsequent release of fluid under pressure from the positioning cylinder devices 3i and 32 and charging of the direct bounce chambers 20 with fluid under pressure.

After the locking devices Q1 have been operated to their locking positions, as just described the operator will let go of the lever 86 whereupon spring 9| will return said lever to its normal position in which it is shown in the drawing and in which the lug 92 is disposed above the projccting end of the plunger 18 in the starting valve device 6%. In the starting valve device @6 spring 83 will then seat valve 12 to cut off further supply of fluid under pressure to passage I it while spring 38 will move the plunger it out of contact with the release valve ii for opening said passage to atmosphere.

Upon opening passage N36 to atmosphere fluid under pressure will be released from chamber 3'! in the positioning cylinder devices 3i and 32 whereupon the pistons 33, dd therein will be returned to their normal position, in which they are shown in Fig. 3, by action of springs 38, as and 45.

Upon release of fluid under pressure from passage Iuii fluid under pressure will be also released from piston chamber H33 in the vent valve device 5'! whereupon spring Hi4 will actuate piston IOI back to its normal position, in which it is shown in the drawing, in order to permit closing of valve 96 by spring 96a. The closing of valve 96 will disconnect from atmosphere the passage Hi l and thereby pipe I8, the storage reservoir 28a and air compressing chambers I5.

Immediately following closing of the valve 96 in the vent valve device 6'1 the pressure of fluid in chamber I3! in theishuttle valve device 63 will become sufiiciently reduced through choke Hi6 and the vented passage Idii to permit spring I36 to return said piston to its upper position in which it is shown in the drawing for unseating valve I26 from seat i 29 and for seating it against seat I3I. The seating of valve lZB against seat I3I will close the atmospheric connection to the direct bounce chambers 2 via passage I32 and open said chambers to pipe I28a leading to the direct bounce governor device I30.

Upon operation of the shuttle valve device 68 to disconnect the direct bounce chambers 29 from atmosphere and to connect them to pipe I-2 8a leading to the direct bounce governor device iill, the pressure of fluid in chamber I65, and thereby in piston chamber ill) which at this time is open to chamber H55 past the valve H3, will promptly reduce by flow into the direct bounce chambers 20. Upon this reduction in pressure in chamber I10 the pressure oi supply fluid in chamber I66 at the opposite side of piston G69 will actuate said piston to unseat valve :63 against the opposing force of spring lfit whereupon fluid under pressure from passage 262 will flow past said valve to chamber Ififi and then into the direct bounce chambers 29 for charging said chambers.

As fluid under pressure is thus supplied to the direct bounce chambers til it will flow by leakage past the direct bounce pistons 5 into the safety spaces 30 and act on the ends of said pistons which will move said pistons out of said spaces and bring the ends of the rods 25, 28 into contact with the respective rollers 53 of locking devices d! which will then temporarily step further movement of said pistons. As the direct bounce pistons 6 thus move out of the safety spaces 39 the supply valve 12 in the timing valve device H4 will become seated but the release valve I'l will remain seated as the plunger 18 is moved with the respective rack 23 by pressure of fluid in chambers 14 acting on the piston portion 231 of said plunger, whereby the fluid under pressure in the locking devices ll will be bottled up to maintain said devices effective.

The piston I is in the sequence valve device 69 is at this time seated by spring I25 against the annular seat rib i221, and the chamber Q24 within said seat rib being open to the direct bounce chambers 26 by way of passage I28 and pipe '25, will become charged with fluid at substantially the same time and to substantially the same pressure as effective in the'direct bounce chambers. When the pressure of fluid thus obtained in the direct bounce chambers and in chamber 12 of the sequence valve device 69 is thus increased to a chosen degree, such as 425 pounds, such pressure will overcome the opposingforce of spring I on the piston H6 and start said piston moving away from the seat rib I23. As the piston H6 thus moves out of contact with the seat rib i23 the pressure of fluid effective in chamber I24 within said rib will equalize into chamber lid encircling said rib thereby subjecting the full area of piston lit to such pressure which will create a force so exceeding that of spring I25 as to promptly actuate said piston to move valve I 9! out of contact with seat I ls and into contact with seat III. This movement of valve Iii? into contact with seat III will close communication between the tim ing valve device Il and the locking devices 41 while the disengagement of said valve from seat I'ilS will open pipe 5-; from said locking devices to atmosphere through a passage Hi3, whereby the fluid under pressure present in chambers 53 in the locking devices will be suddenly released. The springs 52 in the locking devices 41 plus the pressure of fluid in the direct bounce chambers '20 acting through the direct bounce pistons '6 accuses '16 on rods 26, 28 will then disengage said locking devices from said rods and permit said pressure of fluid to move the two piston assemblies from their cute positions in the direction of each other.

As the two piston assemblies thus move under pressure of fiuid in the direct bounce chambers 20,. the plunger It or" the timing valve device lid will move with the respective rack 23 until the release valve ll therein is unseated by engagement with shoulder 8'4 whereupon the fluid under pressure remaining in the release valve chamber l4 and connected pipe lid will be vented through said plunger to atmosphere. When the pressure in chamber "i i acting on the portion 235 of the plunger is thus sufficiently reduced the spring 88 will return said plunger to its normal position in which it is shown in the drawing and in which it will not be contacted by the respective rack 23 during subsequent running of he machine. When the release valve is unseated by shoulder 8 -3 as just described the differential in fluid pressures acting thereon will become so reduced as to permit spring to move said valve out of contact with shoulder 84 so that said valve will remain open as the plunger 18 returns to its normal position, as just mentioned.

As the piston assemblies are moved inwardly toward each other under pressure of fluid in the direct bounce chambers 20 as just described the power pistons t will close first the scavenger port Ill and then the exhaust port 9, following which the air thus trapped between the two power pistons will be compressed and at the proper time the injector s2 will be operated the cam 53 to inject fuel into the power chamber l through the nozzle 3 to provide compression ignition for developing power to stop inward movement or" the piston assemblies and to drive them apart. t will be noted that since the pipe id and storage reservoir itc were vented to atmosphere preliminary to starting, that the fuel control motor sac will position rack E l to provide for a maximum supply of duel by the injector 82 on the initial starting stroke of the piston assemblies.

As the two piston assemblies move inwardly on their initial stroke the air present in the scavenger compressing chambers ii will be forced past the discharge valves 54 into the scavenger receiver I3, the air compressing chambers I5 will be filled with air by way of the intake valves it, while the pressure of fluid. in the direct bounce chambers 28 will reduce as the volume of said chambers is suddenly increased by the inward movement of the two direct bounce pistons 6. As the piston assemblies then more apart on their initial power stroke by the force created by combustion of fuel in the power chamber I, the scavenger pressure chambers I i will be refilled with air past the intake valves it? while the air present in the air compressing chambers I5 will be discharged past the discharge valves I! into the pipe I8 and thence to the storage reservoir IBa. Also on this initial outward stroke of the piston assemblies air present in the direct bounce chambers 29 will be compressed to a degree which, co-acting with the pressure created in the air compressing chambers IE, will stop said piston assemblies short of entering the safety spaces Bil and provide energy for returning said pistons on the following inward stroke.

The direct bounce governor device I36 is automat-ically operative during running of the machine to so regulate the amount of air in the direct bounce chambers 20, with respect to the amount of fuel supplied to power chamber 1 for driving the pistons apart, and also with respect to the energy of the air remaining in the air compressing chambers I5 at the end of the outward stroke of the piston assemblies, as to stop the piston assemblies at the proper position on their outward stroke, and to provide the energy required for returning said assemblies to a chosen inner position.

When the direct bounce chambers 20 are initially charged with fluid under pressure by the direct bounce governor device I30 preparatory to starting the compressor, the pressure of such fluid may, as above mentioned, be for instance 425 pounds at the time the sequence valve device 69 operates to effect release of the locking devices 11 to permit the'initial inward stroke of the piston assemblies. At this time the pressure of fluid in diaphragm chamber I81 of the direct bounce governor device will be of substantially the same value'as thatsupplied by feed valve device 61a, while in chamber I83, which is connected to the direct bounce chambers Zdthrough the small flow capacity pipe I88, the pressure of .fluid at the time the sequence valve device 59 operates, may be somewhat less than in the direct bounce chambers 20, so that the diaphragm I85 will still hold the valve I13 open for venting piston chamber I to the direct bounce chambers to permitthe supply pressure in chamber I60 to hold said piston in the position in which the valve I63 is still open for supplying fluid under pressure to the direct bounce chambers 20.

On the initial inward stroke of the piston assemblies, however, the pressure of fluid in diaphragm chamber I83 will start gradually reducing through pipe I88 due to the sudden reduction in pressure in the connected direct bounce chambers as but this reduction in pressure in chamber !83 in itself will be of no immediate conse quence since it is efiective merely to permit diaphragm 185 to hold the valve I13 open for continuing the supply of fluid under pressure to the direct bounce chambers by way of the open supply valve I 63.-

The energy of the air in the direct bounce chambers 20 will be greater on the initial few inward strokes of thepiston assemblies than required during subsequent running, and as a result these inward strokes of said assemblies will be longer than desired for-running. Due to this, on each inward stroke of the piston assemblies the respective rack" 22'Vwill operate plunger 2| 2 in the direct bounce governori'device to unseat the valve 200 a distance equal substantially to the overstroke of said piston assemblies. This unseating of valve 200 willrelease fluid under pressure fromgchamber I812toilthedirect bounce chambers 26 at a rate exceeding the supply through choke I89 to permita. reduction in pres sure of fluid in said. chamber governed by the length of timewhich' the valve 200 is unseated or the distance which it is unseated by the plunger 2I After one or more inward strokes of the piston assemblies the pressure of fluid in dia phragm, chamber '.I81 will be thus so reduced with respect to the opposing pressure of fluid in chamber I83 as to permit the deflection of diaphragm 885 by said opposing pressure to permit closing of the supply valve I13, whereupon the pressure of fluid in piston chamber I10 will become equal iized tm'ough-choke I 151 and passage I12 with that 18 in the supply passage I62 to permitclosing of the valve I63 by spring I68. After one or more further overstrokes of the piston assemblies in the inward direction the intermittent opening of valve 200 will effect sufiicient further reduction in pressure of fluid in diaphragm chamber I81 to permit the pressure of fluid in chamber I83 to deflect diaphragm I85 further in the direction of the left hand to permit opening of the release valve I16 for thereby releasing fluid under pressure from the direct bounce chambers 20. As the.

amount of fluid in the direct bounce chambers 20 is thus reduced the length of the inward, overstroke of the piston assemblies will be correspondingly decreased, until eventually, the intermittent but reduced opening of valve 200 with respect to the flow capacity of choke I89 for supplying fluid under pressure to chamber I81 will provide a pressure in chamber I81 so related to the mean direct bounce chamber pressure effective in chamber I83 at the opposite side of diaphragm I85 that said diaphragm may remain in a position in which the valve I16 is closed as well as the valve I13. In case of leakage of fluid under pressure from thedirect bounce cha n;

bers 20 to, for instance, the air compressing chamber I5, which would tend to reduce the in}- ward stroke of the piston assemblies, the valve 200 will be unseated on the inward stroke to a corresponding less extent or for aless period of time so that the pressure of fluid in diaphragm chamber E81 will be reduced only to a degree sufficiently in excess of that in chamber I83 to maintain the valve I13 unseated to a degree just sufflcient to oflset such-leakage.

It will thus be seen that during the first few strokes of the free piston air compressor, the direct bounce governor device I30, as controlled by the overstroke of the piston assemblies in the inward direction will automatically reduce the amount of air in the direct bounce chambers 20 to the degree required to cause movement of the piston assemblies only to the chosen innerposition. The adjusting screw 201 in the direct bounce governor device is provided for adjusting the seat for valve 200 for in cooperation with said valve determining the end of the inward stroke of the piston assemblies during running of the machine.

The energy of the air in the clearance space in the air compressing chambers I5 at the end of the outward air compressing stroke of the piston assemblies acts in conjunction with the energy of the air in the direct bounce chambers 20 for movin the piston, assemblies inwardly, andthe former energy varies in accordance with the pressure of air in pipe I 8 and storage reservoir Ilia, but the direct bounce governor device I30 will automatically vary the amount of air in the direct bounce chambers 20 inversely in proportion to the energy of the air in the air compressing chambers I5 at the end of the air compressing stroke so that the combined energies will always'be such as to maintain the desired inner .dead center point of the power pistons as will be apparent from the above description.

The pressure of spring 7229 in the fuel con trol motor M8 is such as tomaintain the dia phragm H9 and thereby the lever 222, and fuel control rack 64 in the position in which they are shown in the drawing, providing for a maximum supply of fuel to the power chamber 1, until the pressure of fluid in the storage reservoir I8a and pipe I8 effective in diaphragm chamber 220 is increased to a chosen degree, such for example encased 19' as 90' pounds, Asthis pressure in diaphragm chamber 220 is further increased the diaphragm 219 is adapted to move against the spring 229 for operating the. rack. 64 to reduce the: supply of fuel to-the power chamber I correspondingly As the supply ofv fuel to the power chamber 1 is thus reduced the force developed on the power pistons 4 by the combustion of such fuelv and thereby the outward stroke of the piston assem blies-will be correspondingly reduced, until at. the time a chosen maximum. pressure (10- pounds) is obtained in the storage: reservoir I8'a and; diaphragm chamber 220,, the lever 224- and rack 64 will obtain an idle: position to provide a minimum supply of. fuel to the power chamber 1.. When the I supply of fuel tothe power chamber I is thus reduced to aminimum the explosive force thereof onthe power pistonassemblies will be insufflcientto increase the pressure of air in the air I compressing chambers L5 to a degree exceeding that already present in. the storage reservoir l8a under which condition. the piston assemblies will merely idleunder the reduced explosive force in chamber I, and against the direct bounce pressure in the direct bounce chambers 21! without compressing air into the storage reservoir I8 the direct bounce governor device I30 operating at all times to maintain a sufficient quantity of air in. the direct bounce chambers for moving the piston assemblies to their inner chosen positionl- As before described, pipe I8 is connected through the unloading valve device 10 topipe I 45 leading to the auxiliary high pressure compressor I41. The hichpressure compressor I41 is operated by the pinion gear operated shaft at all times the free piston compressor I is in operation and takes air from pipe I46, at the pressure present in the storage reservoir I811, and compresses it into pipe I48 and thence through passage I58 and past the check valve I55 in the unloading device 10 to passage I55 and through pipe 95 to the high pressure reservoir 94'. The pressure of fluid thus obtained in the high pressure reservoir 94 is effective in chamber I 54a on piston I5l of the unloading, valve device 10 and when such pressure is increased to the chosen degree, for instance 650 pounds, such pressure will overcome the opposing force of spring I54 on said piston and actuate said piston to unseat the check valve I4l. With the check valve I4l unseated: the discharge pipe I48 from the high pressure compressor I41 will be opened to the intake pipe I46 for said compressor and to pipe [8 connected to the storage reservoir I 8a, whereby the high pressure compressor I 41 will be unloaded and further supply of fluid under pressure to the high pressure reservoir 94 will be terminated.

The high pressure reservoir 94 constitutes the source of supply of fluid under pressure by way of feed valve device am to the direct bounce governor device I for supply to the direct bounce chambers 20 during operation of the compressor I, so that as fluid under pressure is used from said reservoir during such operation the unloading device 10 will automatically oper ate to render the high pressure compressor I4! either effective or ineffective to supply fluid under pressure to said reservoir in order to maintain the pressure insaid. reservoir within limits deter-- mined by the pressure of spring I54 acting. on the unloading piston 15!.

In starting the free piston compressor the choke no and volume In restrict rel a i, flu d under pressure from chamber 131 in the shuttle valve device 58 withrespect to the release of fluid under pressure from the positioning: cylinder devices 3|, 32 as above described, whereby, upon release of the operators handle 86 a slight delay (perhaps one second) in. operation of the shuttle valve device 6.8 to connect the direct bounce chambers 20. to the direct bounce governor device I30 results. When, the direct bounce chambers 20' are thus connected to the direct bounce governor device said chambers will charge with fluid under pressure at a very fast rate, and immediately following, the sequence valve device 69; will operate to effect release of the locking devices 41'. The purpose of the delay above" mentioned is to ensure that the piston rods 4| of the positioning cylinder devices 3!, 32 will be returned to their normal position, in which they are shown in the drawing, before. the locking devices 41' release the piston assemblies for movement on their initial inward stroke, so as to prevent the'rods 26, 28 striking the ends of said piston rods on said stroke.

Further in connection with starting the 00m. pressor I piston I H5 in the sequence valve device 69 actuates valve- HI'I to open pipe 54 from the locking devices 4'! to atmosphere when the pressure of fluid in the direct bounce chambers 20 is increased to a certain high pressure, such as 425' pounds, as above described. On the initial inward stroke of the piston assemblies of the compressor l the pressure in chambers I24, I26 of the sequence valve device may reduce by flow back to the direct bounce chambers 20 to a sumci'entl'y low degree to permit spring I25 to return the parts of said device to the position in which they are shown in the drawing and in which pipe 54 from the locking devices 41 is open to pipe H3 from the timing valve device I I4. This has no effectupon operation'of the locking devices however, since the supply" of fluid under pressure to. pipe I 1'3 by way of the timing valve device I It is terminated upon the initial inward stroke of the piston assemblies. However, on the initial power stroke of the power pistons 4 the pressure of fluid in the direct bounce chambers 20 and thereby in chamber I24 of the sequence valve device 88 may be increased to a sufficient degree to effect movement of the piston H6 out of engagement with the seat I 23, but without any effectupon operation of the compressor. The piston H6 in the sequence valve device 69 may thus be alternately unseated and reseated during the first. few power and return strokes of the power pistons 4 but when the amount of fluid under pressure in the direct bounce chambers 20 becomes reduced, as previously described, to that degree which will not cause overstroking of the power pistons 4 in: the inward direction, the maximum pressure or fluid that will then be obtained in the direct bounce chambers 20, for instance 225 pounds, will be insuffl'cientto move the piston I I6 out of contact with seat rib 423 following which, that is, during subsequent running of the compressor I the piston IIB will remain in contact with said seat rib.

In order to stop operation of the compressor I the supply of fuelto the power chamber '1 need only be cut off by any suitable means (not shown), whereupon the pistonv assemblies will move totheir normal inner position upon the initial inward stroke following the cutting-ed of fuel. The pressure of compressed air, but less combustion of fuel, in power chamber I will then move the piston assemblies apart, but on a shortened outward stroke, following which they will move inward on a shortened stroke. Such oscillation of the piston assemblies may; continue for a few,'but ever decreasing length of strokes until eventually said pistons come to rest in some intermediate position in which the valve 208 in the direct bounce governor device I30 will be seated. With the valve 200 seated, the pressure in diaphragm chamber I81wil1 increase to a degree sufficiently exceeding that in chamber I83 to actuate said diaphragm to open the supply valve I13 whereupon fluid will be supplied to the direct bounce chambers 20 and create a force on the direct bounce pistons 6 exceeding the force created by pressure in the power chamber I on the power pistons 4. As the fluid under pressure in the power chamber 1 is then dissipated by leakage, pressure in the direct bounce chambers 20 will move the piston assemblies toward each other until the valve 209 in the direct bounce governor device is opened to a degree to provide for venting of fluid under pressure from diaphragm chamber I81 at a rate exceeding the rate of supply through choke I 83. When this condition is obtained, the pressure in diaphragm chamber I81 will equalize into the direct bounce chambers 20 and diaphragm chamber I83. The diaphragm I85, having a greater area exposed to pressure in chamber I83 than in chamber I31, will then deflect in the direction to open the release valve I16. The fluid under pressure in the direct bounce chambers 20 and diaphragm chambers I83 and I81 will then be dissipated to a mosphere Without any change occurring in position of the parts of the piston assemblies or the direct bounce governor device I39.

After the compressor I is stopped it will be noted that the open valve I16 will permit a continuous flow of fluid under pressure from the high pressure reservoir 94 to atmosphere by way-oi the feed valve device 61a and the open valve 203. This loss is relatively slight, but if the compressor is to remain stopped for any length of time the cut-off valve 235 will be closed to conserve the air in the high pressure reservoir 94 for subsequent starting of the machine.

Summary will automatically operate after starting to maintain a supply of compressed air for external use.

Having now described the invention, what I claim as new and desire to secure by Letters Patent, is:

1. Apparatus for controlling starting of a free piston machine oi the type having direct bounce and air compressing chambers in which energy of compressed air is adapted to move said piston from an outer position to an inner position to provide compression ignition, said apparatus comprising valve means for venting both of said chambers, means for eflecting movement of said piston to said outer position, an operators com trol device for effecting operation of both of said means substantially in unison, and means operable in said outer position for supplying fluid under ressure to said direct bounce chamber.

2. Apparatus for controlling starting of a free piston machine of the type having direct bounce and air compressing chambersin which energy of compressed air is adapted to move said piston from an outer position to an inner position to provide compression ignition, said apparatus comprising valve means operable by fluid under pressure to establish a vent from said chambers and upon release of fluid under pressure to close said vent, means operable by fluid under pressure to move said piston to said outer position and rendered ineflective upon release of fluid under pressure, an operators control device for substantially simultaneously either supplying fluid under pressure to actuate both of said means or for releasing fluid under pressure therefrom, and means operable in said outer position for supplying fluid under pressure to said direct bounce chamber.

3. Apparatus for controlling starting of a free piston machine of the type having direct bounce and air compressing chambers in which energy of compressed air is adapted to move said piston from an outer position to :an inner position to provide compression ignition, said apparatus comprising automatic means for regulating pres sure of fluid insaid direct bounce chamber, valve means operable by fluid under pressure to close communication between said automatic means and direct bounce chamber and to open a vent to said direct bounce chamber, other valve means operable by fluid under pressure for opening a vent to said air compressing chamber, an operators control device for supplying fluid under pressure to actuate both of said valve means substantially simultaneously and for releasing fluid under pressure from both of said valve means simultaneously, and means operable by fluid under pressure supplied by said operators control device to move said piston tosaid outer position and rendered ineffective upon release of such fluid under pressure.

4. Apparatus for controlling starting of a free piston machine of the type having a bounce chamber in which energy of compressed air is adapted to move said piston from an outer position to an inner position to provide compression ignition for starting the machine, comprising'an operators control element, means operable in response to operation of said element by the operator to open a vent from said chamber and to effect movement of said piston to said outer position and operable in response to release of said lever by the operator to close said vent and to efiect a supply of fluid under pressure to said chamber, locking means operable automatically in said outer position to lock said piston against movement, and means operable in response to a chosen increase in pressure in said chamber to release said locking means.

5. Apparatus for controlling starting of a free piston machine of the type having a bounce chamber in which energy of compressed air is adapted to move said piston from an outer position to an inner position to provide compression ignition for starting the machina'comprising an operators control element; vent means for opening a vent from said chamber, positioning means for moving said piston to said outer position, means operable in response to manual operation of said element to eifect operation of said vent means and positioning means and in response to release of said element by the operator to render said vent means and positioning means ineffective and to also supply fluid under pressure to said chamber, locking means rendered effective in said outer position to hold said piston against movement, and means automatically operative upon a chosen increase in pressure in said chamber to render said locking means inefiective.

a? :6. Apparatus for-controllingoperation of a-free piston machine having adirect bounce chamber in which energy of compressedair is adapted to move said piston from .anouter position to an inner position to provide compression ignition, said apparatus comprising automatic means for supplying fluid under pressure to said direct bounce chamber and comprisingmeans cooperable with said piston at said inner position to release fluid under pressure from said direct bounce chamber for regulating the pressure in said bounce chamber, shuttle valve -means operable by fluid under pressure to disconnect said'direct bounce chamber from said automatic means and to open it to a vent and operable from release, of fluid under pressure to disconnect said direct bounce chamber from said vent and open it to said automatic means, positioning means operable by fluid under pressureto move said piston to said outer position and rendered ineffective upon release of fluid under pressure, operators control means selectively operable to either supply fluid under pressure simultaneously to both said shuttle valve means and positioning means or to release fluid under pressure simultaneously therefrom, locking means operable by fluidunder pressure to hold'said piston in said outer posi-- tion and rendered ineffective upon release of fluid under pressure, valve means operable in said outer position of said piston tosupply fluid under pressure to said locking means, and means. operable upon a chosen increase in pressure in said direct bounce chamber to cut off the supply of fluid under pressure to said locking means and to release the fluid pressure therefrom.

7. Apparatus for controlling starting of a free piston machine of the type having a bounce chamber in which energyoi compressed airis adapted to move said piston from an outerposition to an inner position to provide compression ignition, comprising supply means for supplying fluid under pressure to said chamber, positioning means for moving said piston to said outer position, control means operable to open said chamher to either said supply means or to a vent, looking means for holding said piston in said outer position against movement by pressure of fluid in said chamber, means adapted for operation upon a chosen increase in pressure in said chamber to render said locking means ineflective, and control means for effecting operation of said positioning means and of the first named control means to opensaid-chamber to said vent substantially in unison and for also rendering-said positioning means ineffective and for efiecting operation of said first named control means to open said chamber to said supply means, and means for delaying operation of said first named control means to open said chamber to said supply means with res ect to rendering said positioni-ng means ineffective.

-8.-Apparatus for controlling starting of a free piston machine of the type'having a bounce-chamber in which energy of compressed air is adapted to move said piston from an outer position to an inner position to provide compression ignition, comprising supply means for supplying fluid under pressure to said chamber, positioning means operable by fluid under pressure to move said piston to said outer position, shuttle valve means operable by Tfluid under pressure to open said chamber to a vent'and upon release of fluid under pressure to open "said chamber to said supply means, locking means for holding said piston in said'oluter position against movement by pressure of fluid in said chamber, means responsive to a chosen increase in'pressure in said chamber to render said locking means ineffective, control means for at one time simultaneously supplying fluid under "pressure tos'aid positioning means and shuttle means, and for at another time simultaneously releasing fluid under pressure from said positioning means and shuttle means, and means for delaying release of fluid under pressure from said shuttle means with respect to releaseof fluid under pressure i'rom said positioning means.

'9. Apparatus for controlling starting of a free piston machine of the type "having a bounce chamber in which energy of compressed air is adapted to move said piston from an outer position to an inner position to provide compression ignition and said piston being movable past said outer position, comprising positioning means for moving said piston past said outer position, locking means operable by fluid under pressure for holding said piston for movement from said outer position to said inner position and rendered inefiective upon release of fluid under pressure, valve means operable by said piston beyond said outer position to supply fluid under pressure to said locking means, and to hold such fluid under pressure in said locking means in said outer position, supply means for supplying fluid under pressure to said chamber, shuttle means for selectively connecting said chamber either to said supply means or a vent, operators control means for substantially simultaneously, at one time effecting operation of said positioning means and of said shuttle means to connect said chamber to said vent and for at another time rendering said positioning means ineffective and effecting operation of said shuttle means to connect said chamber to said supply means, and means operable upon a chosen increase in pressure of fluid supplied to said chamber by said supply means to release fluid under pressure from said locking means.

ARTHUR J. BENT.

v:lteferen'ces 'Cited'in' the file of this patent UNITED STATES PATENTS Number Name Date "685,704 Wilkinson Oct. 29, 1901 2,116,939 Zahm et al May 10, 1938 2,425,850 Welsh Aug. 19, 1947 -2,a34,280 Morain Jan. 13, 1948 2,434,778 Welsh Jan. 20, 1948 2,434,877 Welsh et a1 Jan. 20, 1948 2,441,195 Hooker May 11, 1948 2,453,516 Kalitinsky Nov. 9, 19 .8 2,463,051 Pateras Pescara Mar. 1, 1949 2,469,739 'Meitz'ler May 10, 1949 2,557,982 Lewis June 26, 1951 2,600,251 Lewis et al June 10, 1952 2,608,052 Bent Aug. 26, 1952 

